The "Aquarius stream": stars of a dwarf galaxy swallowed by our own Milky Way Galaxy, identified by the RAVE team. Visualisation: Arman Khalatyan, AIP.Movies of RAVE stars.

After the bushfire on 13 January, and almost a decade of work, astronomers using a telescope at Siding Spring Observatory in NSW have finished writing the first chapter in the history of our Galaxy.

The research team, from nine countries, has just completed a project called RAVE (the Radial Velocity Experiment), which was aimed at learning where stars in our Galaxy were born, and how the Galaxy has grown and changed over time.

"Since starting in 2003 we've collected data on the brightness, colour, distance and movements of almost half a million stars," said Professor Fred Watson of the Australian Astronomical Observatory, Project Manager for RAVE.

RAVE has revealed a 'dwarf' galaxy swallowed and shredded by our own Galaxy, stars with unusual chemistry, and the way our Galaxy wobbles. It has also re-weighed the Galaxy.

All this has been achieved with the UK Schmidt Telescope, run by the Australian Astronomical Observatory.

The light from the stars was captured with optical fibres, precisely positioned by a robot.

The robot picks up optical fibres, one by one, and places them on a metal plate in the telescope. Each fibre is in the right place to catch the light from a single star. By using many fibres, more than 100 stars can be studied at the same time.

Travelling down the tiny glass threads, the starlight enters an instrument that spreads it out into its component wavelengths or 'colours', the way a prism does.

These colours tell astronomers about the chemical elements a star contains and how it is moving. From that, the astronomers can work out how old the stars are, where they came from, and how they are related.

And that's the key that unlocks the history of our Galaxy.

The countries taking part in RAVE are Australia, Canada, Germany, France, Italy, the Netherlands, Slovenia, the UK and the USA. Professor Matthias Steinmetz, Director of the Leibnitz Astrophysical Institute at Potsdam in Germany, has led the collaboration.

The Australian Astronomical Observatory is our national optical observatory, and is part of the Commonwealth Department of Innovation, Industry, Climate Change, Science, Research and Tertiary Education. It operates the 3.9-m Anglo-Australian Telescope and the 1.2-m UK Schmidt Telescope at Siding Spring Observatory in New South Wales.